How to Turn an Old Satellite Dish Into a Working Radio Telescope

By Sarah Zhang on at

Radio telescopes, which you may remember Jodie Foster intently listening to for signs of alien life in Contact, pluck out radio waves from far away space. Ordinary communications satellite dishes also pick up radio waves, but of manmade origin. So hmm, how easily can you convert one into another? It's totally possible, according to New Zealand astronomers who detail how they turned an obsolete satellite dish into a radio telescope for astronomy.

In 2010, Telecom New Zealand decommissioned one of its satellite antennas. (Satellite dishes are basically parabolically shaped antennae.) The '80s-era antenna had once carried phone calls, internet traffic, and TV, but it was being replaced by underground fibre-optic connections. Plus, it was old and rusty, made all the worse by salt from the nearby ocean. But the 30-metre dish was still a massive piece of infrastructure that worked, so they donated it to astronomers at the Auckland University of Technology.

A paper recently posted on ArXiv goes into exactly how a 30-year-old dish became a radio telescope useful for modern astronomy. The first step was just replacing the rusty bolts. Then they replaced the dish's pointing mechanism, so it could turn the full 270 degrees for radio astronomy, up from 170 degrees before. The antenna also had to be retro outfitted to pick up frequencies relevant for listening to space rather than listening to long-distance phone calls.

The converted antennae could work alone or as part of a larger array. "This 30m antenna adds significantly to New Zealand's capability in radio astronomy with a large surface area and is a highly sensitive instrument capable of significant single dish work," write the authors in the paper. Elsewhere in the world, including Japan and Australia, satellite antennae have been turned into radio telescopes.

For the curious among you who don't have a 30-metre satellite antenna lying around, despair not. Here's how to make a "poor man's radio telescope" from a regular old satellite dish. In fact, here's another more sophisticated version. You probably won't be the first to find any aliens on it, but you can definitely impress some humans. [ArXiv via Tech Review]

Top image via Woodburn et al.